I know that birdie-sync for windows mobile based on active sync, so it's difficult to run it on Linux. For android you have your own mechanism, so why don't you create a Linux version. This would be great and would be the only solution on the market.
So I would be interested where the problems are and if there exists any plans to build an Linux version.

Another user asked the same question by email. I'm not sure if you are the same user or not.
The problem of Linux is simply that it even if important efforts were made in BirdieSync to prepare portability, it requires a new installer, specific adaptations (USB connections, management of storages devices, etc.), and of course new tests. So by now the priority was given to other features. But that may change in the future.

I would prefer a Linux version. Linux and Android are the perfect combination. So then why should we look for any other option. I think most of the users will do the same also. As of now the highest vote is for it only and the rate will increase. A good way to know peoples opinion before making final decision or doing something new. Anyway it was an interesting question to see what we want in future.